In a power conversion device, dead time in which switching signals for upper and lower arms are turned off is provided to prevent short-circuit between the upper and lower arms. In the dead time, output voltage changes in accordance with the polarity of output current, whereby error voltage occurs between a voltage command and the output voltage. Thus, predetermined output voltage cannot be obtained.
In order to solve this problem, a method of adding a dead time correction amount to the voltage command in accordance with the polarity of the output current is known. However, due to a harmonic component and the like contained in the output current, there is a problem that the correction direction oscillates in the vicinity of zero cross of the output current.
In order to solve this problem, a method of specifying an output current waveform function not containing a harmonic component and the like is disclosed (for example, Patent Document 1). In this method, an output current waveform function that corresponds to an ideal output current waveform not containing a harmonic component and the like and that has an undefined coefficient value, is used, and the coefficient of this function is sequentially updated until least-squares error between a current value calculated from this function and an actual output current value is minimized.